Mayor Michael Bloomberg on Friday announced the evacuation of low-lying areas along the Big Apple’s waterfront areas — a New York first — and the Metropolitan Transit Authority shut down the entire subway system from noon on Saturday until Monday morning, effectively confining residents and tourists to shelter. (The subway hasn’t been shut down since 2005’s transit strike, a move that earned jail time for Transit Workers Union prexy Roger Toussaint.)

The Mayor’s Office of Film, Theater and Broadcasting has revoked all filming permits for the weekend (the MOFTB issued a terse statement via its website). Productions currently filming reportedly include Isla Fisher starrer “Bachelorette” and reality shows “Hoarders” and “Clean House.”

The evacuation area for the city includes sections of all five boroughs. Silvercup Studios and Steiner Studios (two of Gotham’s three biggest shooting facilities) sit close to the water in Queens and Brooklyn, respectively (Steiner is at a former Navy yard). Only Kaufman Astoria Studios is located far enough inland to avoid evacuation.

The weather is certain to affect this weekend’s box office, as many of the major theater chains have already decided to close Saturday and Sunday (see separate story).

Disney Theatrical productions announced the cancellation of its Saturday and Sunday shows on Friday afternoon, as did the New York Intl. Fringe Festival, Off Broadway theaterplexes New World Stages and 59E59, and sundry other venues. It’s never good to close the theater on the weekend, especially on Broadway (Saturday night is almost always the performance that packs the house tightest), but everyone is taking the storm seriously.

Newsies kicked into overdrive, as well: “NBC Nightly News” expanded to an hour on Friday to cover the hurricane, with Brian Williams covering from the Jersey Shore (also being evacuated), while ABC’s “Nightline” will focus on Irene, with an updated version airing on the West Coast. NBC is also kicking into high gear with corporate sibling the Weather Channel resources — weather correspondents Bryan Norcross and Jim Cantore will participate in the net’s coverage.

For the weekend, CBS is adding a special hourlong Sunday broadcast called “Irene Strikes” with Scott Pelley anchoring from 11 a.m. — likely the time when the storm will be furthest inland.

Also on the weekend, “Good Morning America” will expand to three hours with George Stephanopoulos and Robin Roberts anchoring from Times Square starting at 7 in the morning.

Cablers, too, entered the fray: CNN has extended coverage planned for Saturday evening from 8 p.m. to midnight, and a three-hour edition of “The Situation Room” is planned for Saturday from 5 o’clock, while MSNBC’s “Hardball” will extend coverage through the weekend, rather than going to tape.

Fox News will reportedly preempt is 10-to-noon block of biz programming, as well as “Huckabee” tomorrow, freeing up time for more Irene coverage. Shepard Smith will be on point for much of the net’s coverage.

One Gotham biz sector looks likely to at least break even during the course of the storm: the local grocery store biz. On Friday, there were lines to get into the huge Trader Joe’s on Brooklyn main drag Atlantic Avenue, and folks looking for canned goods and bottled water at many stores left disappointed.